A Ball for Daisy is a story of loss — a little dog loses her favorite red ball to a much larger dog — but now it's also a story about winning: On Monday, Chris Raschka's book won the American Library Association's Randolph Caldecott Medal for best illustrated story.

It's not Raschka's first Caldecott honor; he won in 2006 for The Hello, Goodbye Window and was a Caldecott honoree in 1994 for Yo! Yes?

A Ball for Daisy is Raschka's first wordless picture book, and it was "certainly a challenge," he tells NPR's Robert Siegel. "It went through many, many variations."

It's not easy to draw the same dog, from different angles, page after page and make her recognizable.

The story was inspired by Raschka's son, who had a beloved ball that was destroyed by a dog. "[It happened] when he was 4 ... and it was such a devastation for him," Raschka says. "It's kind of ... the first time he experienced something he loved ending, and that he couldn't get that back."

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Raschka has illustrated children's books on wide-ranging subjects — from Charlie Parker Played Be Bop to Mysterious Thelonious to Arlene Sardine, the story of a fish who dreamed of becoming someone's breakfast. Raschka has a simple criterion for choosing his subjects:

"Anything that creates a strong emotion in me," he says. "Whether it's music, loss of something, loneliness or friendship — if that emotion is heightened in some way and painted to fit in between the covers of 32 pages, that can become a picture book."